This invention relates to alkaloid-containing microcapsules and a method for producing such microcapsules.
The recently expressed concern about the effects of the combustion byproducts of cigarette smoke on smokers has created a demand for products which may be substituted for tobacco. Optimally, a successful tobacco substitute product should yield smoke which has a substantially lower amount of undesirable components than tobacco smoke, and provide a flavor impact and combustion rate that is acceptably similar to that of tobacco.
One example of a substitute for tobacco is disclosed in U.S. Pat. No. 3,931,824 to Miano et al. The Miano et al. tobacco substitute is basically made up of combustible organic materials, such as cellulose derivatives, and a non-combustible filler material. Additional flavor impact and odor properties of the Miano et al. tobacco substitute are provided by inclusion of a wide variety of additives, such as tobacco extracts, fruit extracts, and various flavorants. In addition, it is disclosed that nicotine and other alkaloid products may be added in controlled amounts.
It is desirable to include nicotine in tobacco substitutes such as those disclosed in the Miano et al. patent, in order to increase the similarity of the flavor impact of the substitute product to that of tobacco. However, because tobacco alkaloids such as nicotine are readily volatile when isolated from tobacco, it has been difficult, if not commercially impractical, to produce a commercially satisfactory tobacco substitute product containing nicotine. For example, in order to handle the tobacco alkaloids in the manufacturing process, safety precautions, such as expensive exhaust and monitoring equipment, would be needed to insure that the tobacco alkaloid vapors in the manufacturing plant would remain at a sufficiently low level. And, in addition to problems encountered in incorporating tobacco alkaloids into tobacco-substitute products, the shelf life of tobacco alkaloid-containing substitute products may not be of a sufficient duration for these products to be commercially practical, due to the relatively rapid rate of volatilization of the tobacco alkaloids.
It has now been found that the manufacturing and packaging difficulties encountered in incorporating tobacco alkaloids into substitute products can be obviated by microencapsulating the tobacco alkaloids and incorporating the produced microcapsules into the substitute product. While many different microencapsulation techniques are known, prior to the present invention it was not possible to microencapsulate tobacco alkaloids using any of the known techniques.
Of the many different microencapsulation processes which are known in the art, processes which utilize liquid-liquid phase separation to provide a material capable of encapsulating liquid core entities appeared to be the more likely processes for forming microcapsules containing a tobacco alkaloid. Generally, such microencapsulation processes, utilizing liquid-liquid phase separation, are carried out by first forming an agitated system which includes (a) a continuous liquid vehicle such as toluene, (b) a dispersion of individual entities of the material to be encapsulated, i.e., the capsule core material which may either be solid particles or droplets of a solution immiscible with liquid vehicle, and (c) a wall forming material in solution in the continuous liquid vehicle. Next, phase separation of the wall forming material from the liquid vehicle is induced, and the wall forming material envelops the capsule core entities to form microcapsules. Finally the capsule wall material is hardened in some manner. Typical such processes are disclosed in U.S. Pat. No. 3,155,590 to Miller et al., U.S. Pat. No. 3,415,758 to Powell et al., U.S. Pat. No. 3,748,277 to Wagner et al., and U.S. Pat. No. 3,674,704 to Bayless et al.
However, tobacco alkaloids are too soluble in a wide variety of organic and inorganic liquids and, as a practical matter, cannot be maintained in only one liquid phase for microencapsulation according to the prior art processes.